#ifndef VY_AIO_H
#define VY_AIO_H

#include <stdint.h>

#include "file_tab.h"
#include "runtime.h"

typedef struct {
    size_t offset;    /**< Starting offset inside the file in bytes */
    size_t num_bytes; /**< Number of bytes to load */
    /** Destination buffer with at least @ num_bytes bytes.
     *  Must be valid until the load is finished.
     */
    void *dest;
    vy_file_id file; /**< Unique identifier for the file */
} vy_file_load;

#define VY_LOAD_BATCH_MAX_SIZE 64

/** A batch of loads that will be started together.
 *
 * The aio system will hand these to the OS.
 */
typedef struct {
    vy_file_load loads[VY_LOAD_BATCH_MAX_SIZE];

    /** Must be smaller or equal to @c VY_LOAD_BATCH_MAX_SIZE */
    unsigned int num_loads;
} vy_load_batch;

#define VY_AIO_INVALID_HANDLE 0

/** Handle for an async io operation. Can be used to query the state and result. */
typedef uint32_t vy_aio_handle;

enum {
    VY_AIO_LOAD_TOO_LARGE = (VY_SUCCESS + 1),
    VY_AIO_TOO_MANY_OPERATIONS,
    VY_AIO_OUT_OF_MEMORY,
};

typedef enum {
    VY_AIO_STATE_INVALID,
    VY_AIO_STATE_PENDING,
    VY_AIO_STATE_FINISHED,
    VY_AIO_STATE_FAILED,
} vy_aio_state;

VY_DLLEXPORT vy_result vySubmitLoadBatch(const vy_load_batch *batch, vy_aio_handle *handles);

VY_DLLEXPORT volatile vy_aio_state vyGetAIOState(vy_aio_handle handle);

/* Blocks until the given operation is no longer pending.
 * Returns the state that caused the wait to end. The handle is still valid after this function returned. */
VY_DLLEXPORT vy_aio_state vyWaitForAIOCompletion(vy_aio_handle handle);

/* Releases the internal storage for the operation.
 * The system is allowed to re-use the same handle value for new operations after this was called.
 */
VY_DLLEXPORT void vyReleaseAIO(vy_aio_handle handle);

VY_DLLEXPORT vy_result vySubmitSingleLoad(vy_file_load load, vy_aio_handle *handle);

/* Convenience wrapper for a single synchronous file load.
 * Returns the state that caused the wait for completion to return. */
VY_DLLEXPORT vy_aio_state vySubmitSingleLoadSync(vy_file_load load);

#endif